/*
 * Copyright 2017 - 2024 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see [https://www.gnu.org/licenses/]
 */

package infra.jmx.export.assembler;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import javax.management.Descriptor;
import javax.management.JMException;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanParameterInfo;
import javax.management.modelmbean.ModelMBeanAttributeInfo;
import javax.management.modelmbean.ModelMBeanOperationInfo;

import infra.aop.framework.AopProxyUtils;
import infra.aop.support.AopUtils;
import infra.beans.BeanUtils;
import infra.core.DefaultParameterNameDiscoverer;
import infra.core.ParameterNameDiscoverer;
import infra.jmx.export.metadata.AbstractJmxAttribute;
import infra.jmx.support.JmxUtils;
import infra.lang.Nullable;

/**
 * Builds on the {@link AbstractMBeanInfoAssembler} superclass to
 * add a basic algorithm for building metadata based on the
 * reflective metadata of the MBean class.
 *
 * <p>The logic for creating MBean metadata from the reflective metadata
 * is contained in this class, but this class makes no decisions as to
 * which methods and properties are to be exposed. Instead it gives
 * subclasses a chance to 'vote' on each property or method through
 * the {@code includeXXX} methods.
 *
 * <p>Subclasses are also given the opportunity to populate attribute
 * and operation metadata with additional descriptors once the metadata
 * is assembled through the {@code populateXXXDescriptor} methods.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @author David Boden
 * @author <a href="https://github.com/TAKETODAY">Harry Yang</a>
 * @see #includeOperation
 * @see #includeReadAttribute
 * @see #includeWriteAttribute
 * @see #populateAttributeDescriptor
 * @see #populateOperationDescriptor
 * @since 4.0
 */
public abstract class AbstractReflectiveMBeanInfoAssembler extends AbstractMBeanInfoAssembler {

  /**
   * Identifies a getter method in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_GET_METHOD = "getMethod";

  /**
   * Identifies a setter method in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_SET_METHOD = "setMethod";

  /**
   * Constant identifier for the role field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_ROLE = "role";

  /**
   * Constant identifier for the getter role field value in a JMX {@link Descriptor}.
   */
  protected static final String ROLE_GETTER = "getter";

  /**
   * Constant identifier for the setter role field value in a JMX {@link Descriptor}.
   */
  protected static final String ROLE_SETTER = "setter";

  /**
   * Identifies an operation (method) in a JMX {@link Descriptor}.
   */
  protected static final String ROLE_OPERATION = "operation";

  /**
   * Constant identifier for the visibility field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_VISIBILITY = "visibility";

  /**
   * Lowest visibility, used for operations that correspond to
   * accessors or mutators for attributes.
   *
   * @see #FIELD_VISIBILITY
   */
  protected static final int ATTRIBUTE_OPERATION_VISIBILITY = 4;

  /**
   * Constant identifier for the class field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_CLASS = "class";
  /**
   * Constant identifier for the log field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_LOG = "log";

  /**
   * Constant identifier for the logfile field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_LOG_FILE = "logFile";

  /**
   * Constant identifier for the currency time limit field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_CURRENCY_TIME_LIMIT = "currencyTimeLimit";

  /**
   * Constant identifier for the default field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_DEFAULT = "default";

  /**
   * Constant identifier for the persistPolicy field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_PERSIST_POLICY = "persistPolicy";

  /**
   * Constant identifier for the persistPeriod field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_PERSIST_PERIOD = "persistPeriod";

  /**
   * Constant identifier for the persistLocation field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_PERSIST_LOCATION = "persistLocation";

  /**
   * Constant identifier for the persistName field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_PERSIST_NAME = "persistName";

  /**
   * Constant identifier for the displayName field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_DISPLAY_NAME = "displayName";

  /**
   * Constant identifier for the units field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_UNITS = "units";

  /**
   * Constant identifier for the metricType field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_METRIC_TYPE = "metricType";

  /**
   * Constant identifier for the custom metricCategory field in a JMX {@link Descriptor}.
   */
  protected static final String FIELD_METRIC_CATEGORY = "metricCategory";

  /**
   * Default value for the JMX field "currencyTimeLimit".
   */
  @Nullable
  private Integer defaultCurrencyTimeLimit;

  /**
   * Indicates whether strict casing is being used for attributes.
   */
  private boolean useStrictCasing = true;

  private boolean exposeClassDescriptor = false;

  @Nullable
  private ParameterNameDiscoverer parameterNameDiscoverer = ParameterNameDiscoverer.getSharedInstance();

  /**
   * Set the default for the JMX field "currencyTimeLimit".
   * The default will usually indicate to never cache attribute values.
   * <p>Default is none, not explicitly setting that field, as recommended by the
   * JMX 1.2 specification. This should result in "never cache" behavior, always
   * reading attribute values freshly (which corresponds to a "currencyTimeLimit"
   * of {@code -1} in JMX 1.2).
   * <p>However, some JMX implementations (that do not follow the JMX 1.2 spec
   * in that respect) might require an explicit value to be set here to get
   * "never cache" behavior: for example, JBoss 3.2.x.
   * <p>Note that the "currencyTimeLimit" value can also be specified on a
   * managed attribute or operation. The default value will apply if not
   * overridden with a "currencyTimeLimit" value {@code >= 0} there:
   * a metadata "currencyTimeLimit" value of {@code -1} indicates
   * to use the default; a value of {@code 0} indicates to "always cache"
   * and will be translated to {@code Integer.MAX_VALUE}; a positive
   * value indicates the number of cache seconds.
   *
   * @see AbstractJmxAttribute#setCurrencyTimeLimit
   * @see #applyCurrencyTimeLimit(Descriptor, int)
   */
  public void setDefaultCurrencyTimeLimit(@Nullable Integer defaultCurrencyTimeLimit) {
    this.defaultCurrencyTimeLimit = defaultCurrencyTimeLimit;
  }

  /**
   * Return default value for the JMX field "currencyTimeLimit", if any.
   */
  @Nullable
  protected Integer getDefaultCurrencyTimeLimit() {
    return this.defaultCurrencyTimeLimit;
  }

  /**
   * Set whether to use strict casing for attributes. Enabled by default.
   * <p>When using strict casing, a JavaBean property with a getter such as
   * {@code getFoo()} translates to an attribute called {@code Foo}.
   * With strict casing disabled, {@code getFoo()} would translate to just
   * {@code foo}.
   */
  public void setUseStrictCasing(boolean useStrictCasing) {
    this.useStrictCasing = useStrictCasing;
  }

  /**
   * Return whether strict casing for attributes is enabled.
   */
  protected boolean isUseStrictCasing() {
    return this.useStrictCasing;
  }

  /**
   * Set whether to expose the JMX descriptor field "class" for managed operations.
   * Default is "false", letting the JMX implementation determine the actual class
   * through reflection.
   * <p>Set this property to {@code true} for JMX implementations that
   * require the "class" field to be specified, for example WebLogic's.
   * In that case, Infra will expose the target class name there, in case of
   * a plain bean instance or a CGLIB proxy. When encountering a JDK dynamic
   * proxy, the <b>first</b> interface implemented by the proxy will be specified.
   * <p><b>WARNING:</b> Review your proxy definitions when exposing a JDK dynamic
   * proxy through JMX, in particular with this property turned to {@code true}:
   * the specified interface list should start with your management interface in
   * this case, with all other interfaces following. In general, consider exposing
   * your target bean directly or a CGLIB proxy for it instead.
   *
   * @see #getClassForDescriptor(Object)
   */
  public void setExposeClassDescriptor(boolean exposeClassDescriptor) {
    this.exposeClassDescriptor = exposeClassDescriptor;
  }

  /**
   * Return whether to expose the JMX descriptor field "class" for managed operations.
   */
  protected boolean isExposeClassDescriptor() {
    return this.exposeClassDescriptor;
  }

  /**
   * Set the ParameterNameDiscoverer to use for resolving method parameter
   * names if needed (e.g. for parameter names of MBean operation methods).
   * <p>Default is a {@link DefaultParameterNameDiscoverer}.
   */
  public void setParameterNameDiscoverer(@Nullable ParameterNameDiscoverer parameterNameDiscoverer) {
    this.parameterNameDiscoverer = parameterNameDiscoverer;
  }

  /**
   * Return the ParameterNameDiscoverer to use for resolving method parameter
   * names if needed (may be {@code null} in order to skip parameter detection).
   */
  @Nullable
  protected ParameterNameDiscoverer getParameterNameDiscoverer() {
    return this.parameterNameDiscoverer;
  }

  /**
   * Iterate through all properties on the MBean class and gives subclasses
   * the chance to vote on the inclusion of both the accessor and mutator.
   * If a particular accessor or mutator is voted for inclusion, the appropriate
   * metadata is assembled and passed to the subclass for descriptor population.
   *
   * @param managedBean the bean instance (might be an AOP proxy)
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return the attribute metadata
   * @throws JMException in case of errors
   * @see #populateAttributeDescriptor
   */
  @Override
  protected ModelMBeanAttributeInfo[] getAttributeInfo(Object managedBean, String beanKey) throws JMException {
    PropertyDescriptor[] props = BeanUtils.getPropertyDescriptors(getClassToExpose(managedBean));
    List<ModelMBeanAttributeInfo> infos = new ArrayList<>();

    for (PropertyDescriptor prop : props) {
      Method getter = prop.getReadMethod();
      if (getter != null && getter.getDeclaringClass() == Object.class) {
        continue;
      }
      if (getter != null && !includeReadAttribute(getter, beanKey)) {
        getter = null;
      }

      Method setter = prop.getWriteMethod();
      if (setter != null && !includeWriteAttribute(setter, beanKey)) {
        setter = null;
      }

      if (getter != null || setter != null) {
        // If both getter and setter are null, then this does not need exposing.
        String attrName = JmxUtils.getAttributeName(prop, isUseStrictCasing());
        String description = getAttributeDescription(prop, beanKey);
        ModelMBeanAttributeInfo info = new ModelMBeanAttributeInfo(attrName, description, getter, setter);

        Descriptor desc = info.getDescriptor();
        if (getter != null) {
          desc.setField(FIELD_GET_METHOD, getter.getName());
        }
        if (setter != null) {
          desc.setField(FIELD_SET_METHOD, setter.getName());
        }

        populateAttributeDescriptor(desc, getter, setter, beanKey);
        info.setDescriptor(desc);
        infos.add(info);
      }
    }

    return infos.toArray(new ModelMBeanAttributeInfo[0]);
  }

  /**
   * Iterate through all methods on the MBean class and gives subclasses the chance
   * to vote on their inclusion. If a particular method corresponds to the accessor
   * or mutator of an attribute that is included in the management interface, then
   * the corresponding operation is exposed with the &quot;role&quot; descriptor
   * field set to the appropriate value.
   *
   * @param managedBean the bean instance (might be an AOP proxy)
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return the operation metadata
   * @see #populateOperationDescriptor
   */
  @Override
  protected ModelMBeanOperationInfo[] getOperationInfo(Object managedBean, String beanKey) {
    Method[] methods = getClassToExpose(managedBean).getMethods();
    List<ModelMBeanOperationInfo> infos = new ArrayList<>();

    for (Method method : methods) {
      if (method.isSynthetic()) {
        continue;
      }
      if (Object.class == method.getDeclaringClass()) {
        continue;
      }

      ModelMBeanOperationInfo info = null;
      PropertyDescriptor pd = BeanUtils.findPropertyForMethod(method);
      if (pd != null && ((method.equals(pd.getReadMethod()) && includeReadAttribute(method, beanKey)) ||
              (method.equals(pd.getWriteMethod()) && includeWriteAttribute(method, beanKey)))) {
        // Attributes need to have their methods exposed as
        // operations to the JMX server as well.
        info = createModelMBeanOperationInfo(method, pd.getName(), beanKey);
        Descriptor desc = info.getDescriptor();
        if (method.equals(pd.getReadMethod())) {
          desc.setField(FIELD_ROLE, ROLE_GETTER);
        }
        else {
          desc.setField(FIELD_ROLE, ROLE_SETTER);
        }
        desc.setField(FIELD_VISIBILITY, ATTRIBUTE_OPERATION_VISIBILITY);
        if (isExposeClassDescriptor()) {
          desc.setField(FIELD_CLASS, getClassForDescriptor(managedBean).getName());
        }
        info.setDescriptor(desc);
      }

      // allow getters and setters to be marked as operations directly
      if (info == null && includeOperation(method, beanKey)) {
        info = createModelMBeanOperationInfo(method, method.getName(), beanKey);
        Descriptor desc = info.getDescriptor();
        desc.setField(FIELD_ROLE, ROLE_OPERATION);
        if (isExposeClassDescriptor()) {
          desc.setField(FIELD_CLASS, getClassForDescriptor(managedBean).getName());
        }
        populateOperationDescriptor(desc, method, beanKey);
        info.setDescriptor(desc);
      }

      if (info != null) {
        infos.add(info);
      }
    }

    return infos.toArray(new ModelMBeanOperationInfo[0]);
  }

  /**
   * Creates an instance of {@code ModelMBeanOperationInfo} for the
   * given method. Populates the parameter info for the operation.
   *
   * @param method the {@code Method} to create a {@code ModelMBeanOperationInfo} for
   * @param name the logical name for the operation (method name or property name);
   * not used by the default implementation but possibly by subclasses
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return the {@code ModelMBeanOperationInfo}
   */
  protected ModelMBeanOperationInfo createModelMBeanOperationInfo(Method method, String name, String beanKey) {
    MBeanParameterInfo[] params = getOperationParameters(method, beanKey);
    if (params.length == 0) {
      return new ModelMBeanOperationInfo(getOperationDescription(method, beanKey), method);
    }
    else {
      return new ModelMBeanOperationInfo(method.getName(),
              getOperationDescription(method, beanKey),
              getOperationParameters(method, beanKey),
              method.getReturnType().getName(),
              MBeanOperationInfo.UNKNOWN);
    }
  }

  /**
   * Return the class to be used for the JMX descriptor field "class".
   * Only applied when the "exposeClassDescriptor" property is "true".
   * <p>The default implementation returns the first implemented interface
   * for a JDK proxy, and the target class else.
   *
   * @param managedBean the bean instance (might be an AOP proxy)
   * @return the class to expose in the descriptor field "class"
   * @see #setExposeClassDescriptor
   * @see #getClassToExpose(Class)
   * @see AopProxyUtils#proxiedUserInterfaces(Object)
   */
  protected Class<?> getClassForDescriptor(Object managedBean) {
    if (AopUtils.isJdkDynamicProxy(managedBean)) {
      return AopProxyUtils.proxiedUserInterfaces(managedBean)[0];
    }
    return getClassToExpose(managedBean);
  }

  /**
   * Allows subclasses to vote on the inclusion of a particular attribute accessor.
   *
   * @param method the accessor {@code Method}
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return {@code true} if the accessor should be included in the management interface,
   * otherwise {@code false}
   */
  protected abstract boolean includeReadAttribute(Method method, String beanKey);

  /**
   * Allows subclasses to vote on the inclusion of a particular attribute mutator.
   *
   * @param method the mutator {@code Method}.
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return {@code true} if the mutator should be included in the management interface,
   * otherwise {@code false}
   */
  protected abstract boolean includeWriteAttribute(Method method, String beanKey);

  /**
   * Allows subclasses to vote on the inclusion of a particular operation.
   *
   * @param method the operation method
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return whether the operation should be included in the management interface
   */
  protected abstract boolean includeOperation(Method method, String beanKey);

  /**
   * Get the description for a particular attribute.
   * <p>The default implementation returns a description for the operation
   * that is the name of corresponding {@code Method}.
   *
   * @param propertyDescriptor the PropertyDescriptor for the attribute
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return the description for the attribute
   */
  protected String getAttributeDescription(PropertyDescriptor propertyDescriptor, String beanKey) {
    return propertyDescriptor.getDisplayName();
  }

  /**
   * Get the description for a particular operation.
   * <p>The default implementation returns a description for the operation
   * that is the name of corresponding {@code Method}.
   *
   * @param method the operation method
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return the description for the operation
   */
  protected String getOperationDescription(Method method, String beanKey) {
    return method.getName();
  }

  /**
   * Create parameter info for the given method.
   * <p>The default implementation returns an empty array of {@code MBeanParameterInfo}.
   *
   * @param method the {@code Method} to get the parameter information for
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @return the {@code MBeanParameterInfo} array
   */
  protected MBeanParameterInfo[] getOperationParameters(Method method, String beanKey) {
    ParameterNameDiscoverer paramNameDiscoverer = getParameterNameDiscoverer();
    String[] paramNames = (paramNameDiscoverer != null ? paramNameDiscoverer.getParameterNames(method) : null);
    if (paramNames == null) {
      return new MBeanParameterInfo[0];
    }

    MBeanParameterInfo[] info = new MBeanParameterInfo[paramNames.length];
    Class<?>[] typeParameters = method.getParameterTypes();
    for (int i = 0; i < info.length; i++) {
      info[i] = new MBeanParameterInfo(paramNames[i], typeParameters[i].getName(), paramNames[i]);
    }

    return info;
  }

  /**
   * Allows subclasses to add extra fields to the {@code Descriptor} for an MBean.
   * <p>The default implementation sets the {@code currencyTimeLimit} field to
   * the specified "defaultCurrencyTimeLimit", if any (by default none).
   *
   * @param descriptor the {@code Descriptor} for the MBean resource.
   * @param managedBean the bean instance (might be an AOP proxy)
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @see #setDefaultCurrencyTimeLimit(Integer)
   * @see #applyDefaultCurrencyTimeLimit(javax.management.Descriptor)
   */
  @Override
  protected void populateMBeanDescriptor(Descriptor descriptor, Object managedBean, String beanKey) {
    applyDefaultCurrencyTimeLimit(descriptor);
  }

  /**
   * Allows subclasses to add extra fields to the {@code Descriptor} for a
   * particular attribute.
   * <p>The default implementation sets the {@code currencyTimeLimit} field to
   * the specified "defaultCurrencyTimeLimit", if any (by default none).
   *
   * @param desc the attribute descriptor
   * @param getter the accessor method for the attribute
   * @param setter the mutator method for the attribute
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @see #setDefaultCurrencyTimeLimit(Integer)
   * @see #applyDefaultCurrencyTimeLimit(javax.management.Descriptor)
   */
  protected void populateAttributeDescriptor(
          Descriptor desc, @Nullable Method getter, @Nullable Method setter, String beanKey) {

    applyDefaultCurrencyTimeLimit(desc);
  }

  /**
   * Allows subclasses to add extra fields to the {@code Descriptor} for a
   * particular operation.
   * <p>The default implementation sets the {@code currencyTimeLimit} field to
   * the specified "defaultCurrencyTimeLimit", if any (by default none).
   *
   * @param desc the operation descriptor
   * @param method the method corresponding to the operation
   * @param beanKey the key associated with the MBean in the beans map
   * of the {@code MBeanExporter}
   * @see #setDefaultCurrencyTimeLimit(Integer)
   * @see #applyDefaultCurrencyTimeLimit(javax.management.Descriptor)
   */
  protected void populateOperationDescriptor(Descriptor desc, Method method, String beanKey) {
    applyDefaultCurrencyTimeLimit(desc);
  }

  /**
   * Set the {@code currencyTimeLimit} field to the specified
   * "defaultCurrencyTimeLimit", if any (by default none).
   *
   * @param desc the JMX attribute or operation descriptor
   * @see #setDefaultCurrencyTimeLimit(Integer)
   */
  protected final void applyDefaultCurrencyTimeLimit(Descriptor desc) {
    if (getDefaultCurrencyTimeLimit() != null) {
      desc.setField(FIELD_CURRENCY_TIME_LIMIT, getDefaultCurrencyTimeLimit().toString());
    }
  }

  /**
   * Apply the given JMX "currencyTimeLimit" value to the given descriptor.
   * <p>The default implementation sets a value {@code >0} as-is (as number of cache seconds),
   * turns a value of {@code 0} into {@code Integer.MAX_VALUE} ("always cache")
   * and sets the "defaultCurrencyTimeLimit" (if any, indicating "never cache") in case of
   * a value {@code <0}. This follows the recommendation in the JMX 1.2 specification.
   *
   * @param desc the JMX attribute or operation descriptor
   * @param currencyTimeLimit the "currencyTimeLimit" value to apply
   * @see #setDefaultCurrencyTimeLimit(Integer)
   * @see #applyDefaultCurrencyTimeLimit(javax.management.Descriptor)
   */
  protected void applyCurrencyTimeLimit(Descriptor desc, int currencyTimeLimit) {
    if (currencyTimeLimit > 0) {
      // number of cache seconds
      desc.setField(FIELD_CURRENCY_TIME_LIMIT, Integer.toString(currencyTimeLimit));
    }
    else if (currencyTimeLimit == 0) {
      // "always cache"
      desc.setField(FIELD_CURRENCY_TIME_LIMIT, Integer.toString(Integer.MAX_VALUE));
    }
    else {
      // "never cache"
      applyDefaultCurrencyTimeLimit(desc);
    }
  }

}
